Principal Investigator/Program Director (Last, First, Middle: Chen, Ridong Abstract Type-2 diabetes (T2D) is a leading cause of cardiovascular disease, renal failure, blindness, amputations and hospitalization. Up to 80% of T2D patients are overweight or obese, which induces chronic, low-grade inflammation of adipose tissue and promotes insulin resistance and T2D. Moreover, weight gain is the common side-effect of older anti-diabetic drugs. Current therapies are not a cure and require daily administration. Hence, novel therapy that improves glucose control while simultaneously reducing body weight is urgently needed. CD4+CD25+Foxp3+ regulatory T cells (Treg) modulate inflammation and insulin resistance. Very interestingly, Treg cells with a unique phenotype are highly enriched in the visceral adipose tissue (VAT) of normal animals, but their numbers are strikingly and specifically reduced in insulin-resistant models of obese animals. Importantly, decreased numbers of Treg are also found in obese human omental. Interleukin-2 (IL-2) is the key cytokine for the generation, survival, and function of Treg by direct binding to its high affinity receptor. Hence, restoration of VAT Treg cells with low-dose IL2 may offer a novel strategy for mitigating obesity related low-grade inflammation and reversing insulin resistance and T2D. We have designed an IL2-based therapy that will enable selective stimulation of Tregs. In the proposed Phase I SBIR study, we will determine whether weekly treatment for 4 weeks leads to improvement of insulin sensitivity and glucose control, while reducing excessive body weight gain in the T2D models of obese db/db mice and diet-induced obese mice. The long-term goal of this project is to develop a novel treatment (weekly or bi-weekly) for T2D, alone or in combination with current therapies, to improve glucose homeostasis and attenuate diabetes-associated complications while simultaneously reducing excessive body weight gain.